RE: st: RE: puzzling "missing" before and after "gen newvar = mdy(a, b, c)"

[Michael McCulloch <mm@pinest.org>]

Thanks Nick; this had just occurred to me.
I was able to ferret out where the out-of-range days & months were:

BEFORE
. tostring datedx, replace
        datedx was double now str8
. generate str4 dxyr1= substr(datedx,1,4)
. generate str2 dxmo1 = substr(datedx,5,6)
. generate str2 dxda1 = substr(datedx,7,8)
. destring dx*, replace
        dxyr1 has all characters numeric; replaced as int
        dxmo1 has all characters numeric; replaced as byte
        dxda1 has all characters numeric; replaced as byte
. gen datedx1 = mdy(dxmo1, dxda1, dxyr1)
(667 missing values generated)

AFTER
. tostring datedx, replace
        datedx was double now str8
. generate str4 dxyr1= substr(datedx,1,4)
. generate str2 dxmo1 = substr(datedx,5,6)
. generate str2 dxda1 = substr(datedx,7,8)
. destring dx*, replace
. drop if dxmo==99
        (233 observations deleted)
. drop if dxda==99
        (434 observations deleted)
. gen datedx1 = mdy(dxmo1, dxda1, dxyr1)
*** no more missing; thanks for your help!***







At 02:05 PM 1/11/2007, you wrote:
> I am glad you are making progress, but if you have any "99"
> for month and day, i.e. missing values encoded as such,
> then -todate- has no way to work out the correct values.
> So, your dates should still be missing in the same place.
> It's just that -todate- doesn't squawk at you about them. At this point,
> I am not sure that is a feature.
>
> Nick
> n.j.cox@durham.ac.uk
>
> Michael McCulloch
>
> > Thanks Nick; using -todate-, now the missing values are no
> > longer generated.
> >
> > . todate datedx , gen(datedx2) pattern(yyyymmdd)
> > . format datedx2 %d
> >
> > Out of curiosity, I looked back at my previous method, and
> > found that there
> > were day and month ==99.
> >
> > . summarize dx??1
> >      Variable |       Obs        Mean    Std. Dev.       Min
> >       Max
> > -------------+--------------------------------------------------------
> >         dxyr1 |     26806    1990.195    1.958295       1987
> >      1993
> >         dxmo1 |     26806    7.269828    9.244575          1
> >        99
> >         dxda1 |     26806    17.66037    15.60529          1
> >        99
> >
> > >summarize dx??1
> > >
> > >to see which of the days, months, years variables are
> > >out of range.
> > >
> > >Anyway, why are you doing it this way? Only a few days ago
> > >a thread you started thrashed out the fact that -todate- from SSC
> > >should be able to do it in one line.
> > >
> > >todate datedx, pattern(yyyymmdd) format(%d) gen(datedx1)
> > >Michael McCulloch
> > >
> > > > I've converted a string date (yyyymmdd) to Stata format, using:
> > > >
> > > > . * convert datedx to Stata format
> > > > . tostring datedx, replace
> > > >          datedx was double now str8
> > > > . generate str4 dxyr1= substr(datedx,1,4)
> > > > . generate str2 dxmo1 = substr(datedx,5,6)
> > > > . generate str2 dxda1 = substr(datedx,7,8)
> > > > . destring dx*, replace
> > > >          dxyr1 has all characters numeric; replaced as int
> > > >          dxmo1 has all characters numeric; replaced as byte
> > > >          dxda1 has all characters numeric; replaced as byte
> > > > . gen datedx1 = mdy(dxmo1, dxda1, dxyr1)
> > > >          (387 missing values generated)
> > > > . format datedx1 %d
> > > >
> > > > However, search for missing values before & after my commands
> > > > yields nothing:
> > > > . list datedx if missing(datedx) in 1/10
> > > >
> > > > Where might the missing 387 values have originated?
>
> *
> *   For searches and help try:
> *   http://www.stata.com/support/faqs/res/findit.html
> *   http://www.stata.com/support/statalist/faq
> *   http://www.ats.ucla.edu/stat/stata/

Best wishes,
Michael


____________________________________

Michael McCulloch
Pine Street Clinic
Pine Street Foundation
124 Pine Street, San Anselmo, CA 94960-2674
tel     415.407.1357
fax     415.485.1065
email:  mm@pinest.org
web:    www.pinest.org
        www.pinestreetfoundation.org
        www.medepi.net/meta





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